Furnace



' March 27, 1928.

W. A. GILCHRIST FURNACE Original Filed July 8, 1919 Inzrenor:

Patented Mar. 27, 1928.

UNITED STA WILLIAM A. GILCHRIST, OF NEW YORK, N. Y;

FURNACE.

Application filed July 8, 1919, Serial No. 309,340. Renewed July 2,1928.

. The invention relates to steam boiler furnaces and has for its objectthe provision of a furnace ofimproved design having particular referenceto securing increased capacity with fuel of low grade while stillinsuring complete combustion and economical use of the selectedfuel. I

As the combustion of solid fuel comprises the production of combustiblegases by destructive distillation of the fuel in the first instance, andthen'the burning of the gases so produced, the total capacity of thefurnace for economical use of the fuel depends both upon its capacityfor destructive distillation of the solid fuel and its capacity forburning combustible gases to good advantage. Furthermore, as low gradefuels usually contain but small amounts offixed carbon and produce'gasesof only relatively low heating value, the proportion of the total heatof combustion derived from the burn- .ing gases is larger than in thecase of better fuels and larger amounts of gas must be produced andburned. And finally, ,as some of the low grade fuels contain moisture inamounts equal to and even exceeding the weight of dry fuel, thismoisture must be evaporated from the fuel bed and the resulting watervapor substantially dilutes the combustible gases. 7

It follows that, particularly with low grade wet fuels, the relativelysmall amount of combustion which takes place in the fuel bed cannot berelied upon to provide sufficient heat for'the rapid drying anddestructive distillation of fresh fuel andnot only must ample provisionbe made for the complete combustion of the combustible gases but thesegases must be burned in such relation to the fuel bed that the heatgenerated by their combustion will be effective to promote drying and.destructive distillation of the fuel in addition to heating the steamboiler with which the furnace is associated. The invention accordinglycontemplates an improved construction of steam boiler furnace comprisinga fiat sloping arch which extends entirely over the firebox and acombustion chamber of large capacity having direct open communicationwith the fire box from the grate level to the higher end of the saidarch, one embodiment ofthe im- I proved construction being illustratedin the accompanying drawings, wherein Fig. 1 is a central longitudinalview, and

sectional Fig. 2 is a" detail transverse sectionalview taken on the'line 22 of Fig. 1.

When the improved furnace is associated with a steam boiler, as 11, thefire box 10 is preferably located in front of the forward end of theboiler as is quite common in socalled extended front or Dutch ovenfurnaces, but withvthe boiler 11 supported at a much greaterelevation'above the level of the grate 12 than has heretofore been,thecustomary practice. When sawdust or the like is to be used as fuel itis desirable that the fuel heap, indicated at13, should be disturbed aslittle as possible. The grate12 is accordingly shown as being of theconventional stationary type.

In carrying out the invention, the roof 14 of the fire box isconstructed to be heated not only from the burningfuel within the firebox but also from the combustion of gases beyond, the end of the firebox and for directing heat upon the fuel heap to assist in the dryingand destructive distillation of the fuel. For this purpose, the roof 14is made in theform of a flat masonry arch which slopes upwardly andrearwardly, 7

preferably throughout its entire length, whereby its under surface facesdownwardly and rearwardly at a substantial angle. As the fire box 10opens directly into a commodious combustion chamber 15, no support isprovided under the rear end of the roof 14 but this may be hung fromatransverse beam or channel 16 in accordance with the well knownpractice of supporting flat arches.

The combustion chamber 15 is shown as being located under the forwardend of the boiler 11. It has a masonry floor 17 preferably located atthesame level and equal in'extent with the grate 12, and an uprightmasonryrear wall 18 the top of which is only sufficiently removed fromthe underside of the boiler to provide flue space 19 extending totherear end of the boiler. The combustion chamber 15 also has a masonryfront wall 20 extending from the level of the rear-end of the fire boxroof 14 to the underside of the boiler and it is of course bounded atthe sides by the masonry walls of the boiler setting.

The invention contemplates that the height and longitudinal depth of thecombustion chamber 15 shall be suchas to provide sufficient capacity forcomplete combustion of the furnace gases before entering the flue.

19. Under these circumstances the masonry wall 18 becomes highly heatedand, by reason of the elevation of the rear end of the fire box roof 14,is effective throughout substantially its entire height in radiatingheat back into the fire box chamber. Drying and destructive distillationof the fuel are thereby materially aided, both by the combustion of thefurnace gases in immediate proximity to the fuel without any interveningobstruction and by the radiating and reflection of heat upon the fuelfrom the masonry walls of both the fire box and combustion chamber.Likewise, there is ample time for complete combustion of the furnacegases before they are chilled by contact with the boiler shell wherebylow grade fuels maybe used economically and without the, production ofsmoke.

' -lVhile thesloping arrangement of the fire box roof- 14: has the usualadvantage in providing increased volume in the rear end portion of thefire box and a free exit for the furnace gases it has, in this instance,the added: advantage-of providing an unobstructed path for heatradiating from the upper portion of thewall 18 to the fuel bed andfacing the said rear wall 18 to be heated therefrom. The arch 14, theheat reflecting wall 18 and the floor 17 will usually be formed ofrefractory clay products commonly termed masonry. The word masonry, asemployed in the description and claims, is not however,limited withrespect to the particularcomposition of the refractory material employedfor these parts. I

I claim as my invention:

1. In a furnace, in combination, a fiat horizontal grate for supportingthe fuel bed, a flat masonry arch sloping upwardly at a substantialangle from its forward end and extending over the grate, the said archconstituting an inclined roof for a firebox chamber which is open at itsrear vend throughout the width of the grate and arch and fromsubstantially the grate level to the level of the rear end of the arch,an. upright transverse masonry heat storage and refleotjing wallextending from the grate level sub stantially to the plane of the archbut located beyond the rear ends of the grate and arch andfacing'directly into the fire box chamber, and an upwardly facing.masonry 'fioor extending substantially at the grate level, from the rearend of the grate to the said upright wall andconstitutingwith thelatterthe floor and end respectively of a combustion chamber adjoiningthe fire box and opening upwardly between the rear end .of, the arch andthetop of the said upright wall for the delivery of products ofcombustion and direct radiation of heat to. a iste'am'boiler or thelike.

2. In a furnace, in combination, a grate,

a masonry arch sloping upwardly at'a substantial angle from its forwardend and extending over the grate, the said arch constituting aninclined. roof for a fire box chamber which. is open at its rear endarch but located beyond the rear .ends of the constituting with the saidupright wall the I floor andend respectively of a combustion chamberadjoining the fire .box and opening upwardly betweenthe rear end of thearch and the said upright wall for the delivery of products ofcombustion and direct radiation of heat to a steam boiler or the like.3. In a furnace,'the comblnation of a grate, a refractory arch slopingupwardly at a substantial angle from its forward end and extending overthe grate and constitutfire-box, the floor and, wall partially form inga combustion chamber in open communication with the fire-box throughoutthe width of the grate-and arch 'andfapproximatelyfrom the level of therear end of the grateto the level of the rear end of the 'archand'havingan opening for the transmission of heat to a steam boiler orthe hke.

' 4-. In a furnace, the combination 'of a grate, a refractory arch abovethe grate sloping upwardly at a substantial angle from its forward endand constituting thereof of a fire-box,,a refractory floor extendingrearwardly from the fire-box at approximately the level of the rear endof the grate,'and

a transverse refractory heat storage and reflecting wall extendingupwardly from the floor ,rearwardly beyond the fire-box 'and' facingthefire-box, the floor and'wallforming part'of a combustion chamber in opencommunication with the fire-box" approximately'throughout the widthandheight of V the rear end of the fire-box and having an opening forthe transmission of heat toa steam boiler orthe like. 7

5. In a'furnace, the combination of a sloping upwardly ata substantialangle from its forward end and constituting'the roof V. grate, aflatrefr'actory arch above the grate n of a fire-box, a refractory floorextending rearwardly from the fire-box at approximately the level of therear end of the grate, and a transverse refractory heat storage andreflecting wall extending upwardly from the fioor rearwardly beyond thefire-box and fa cing the fire-box, the floor and wall forming two sidesof a combustion chamber in open communication with the fire-boxapproximately throughout the width and height of the rear end of thefire-box and having an opening for the transmission of heat to a steamboiler or the like. I

6. In a furnace, the combination of a hori- Zontal grate, a fiatrefractory arch above the grate sloping upwardly at a substantial anglefrom its forward end and constituting the roof of a fire-box, arefractory floor extending rearwardly from the fire-box at approximatelythe level of the grate, and a transverse refractory heat storage andreflecting wall extending upwardly from the floor rearwardly beyond thefire-box and facing the fire-box, the floor and wall forming the bottomand back of a combustion chamber in open communication with the fire-boxapproximately throughout the width and height of the rear end of thefire-box and having anopening for the transmission of heat to a steamboiler or the like.

7. In a furnace, the combination of a horizontal grate, a flatrefractory arch above the grate sloping upwardly at a substantial anglefrom its forward end and constituting the roof of a fire-box, arefractory floor extending rearwardly from the fire-box at approximatelythe level of the grate, a trans verse refractory heat storage andreflecting wall extending upwardly from the floor rearwardly beyond thefire-box and facingvthe fire-box, the floor and wall forming two wallsof a combustion chamber in open communication with the fire-boxapproximately throughout the width and height of the rear end of thefire-box, and a refractory wall extending upwardly from the rear end ofthe arch and facing said transverse wall and forming therewith anopening for the transmission of heat to a steam boiler or the like.

8. A furnace comprisin a fire box chamber, means for supporting ueltherein, an inclined refractory arch extending over the fuel rearwardlyand upwardly to a height substantially higher than the fuel, acombustion chamber in substantially unobstructed communication with therear end of the fire forwardly against the fuel in the fire box chamber,and also against said arch, by which heat is reflected and radiatedagainst the fuel, and a flue connected with the combustion chamber forexhausting the heated gases.

9. A furnace comprising a fire box chamber, provided with means forsupporting fuel therein, a combustion chamber in substantiallyunobstructed communication with said fire box chamber from top to bottomthereof and extending rearwardly therefrom for retaining, during theircombustion, the combustible volatiles issuing from the fuel, saidcombustion chamber including a floor extending rearwardly fromapproximately the bottom of the fire box chamber, and a transverse wallextending from said floor to the full height of the fire box chamber andfacing the fire box chamber for reflecting and radiating heat forwardlythereinto, a dlS-.

charge flue connected with the combustion chamber, and an inclinedrefractory arch ex tending over. the fuel rearwardly and upwardly to alevel above the hottest zone in the combustion chamber, whereby heatreceived from said combustion chamber and from said .wall is reflectedand radiated therefrom against the fuel.

WILLIAM A. GILCHRIST.)

